Effect of Milling and Filtration Methods on Yield of Dried Soybean Sheet

Despite efforts attempting to increase the protein extraction rate from soybeans in dried soybean sheet production,the recovery rate remains less than 50%.This article reviews the factors affecting the yield,and presents the results from our experimentation targeted at the soybean-milling and slurry-filtration of the protein extraction prior to sheet formation.The traditional sand and colloid grinder milling methods,ratio of soybeans to water,milling time and particle size were examined.The orthogonal experimentalresults showed that a multiple stage separation should be used for the process.A maximized protein recovery could be obtained by a two-stage filtration:firstly,using the sand milling with a water/soybean ratio of 4.5/1to grind the soybeansfollowed by filtration through a 80 mesh silk cloth;then,applying the colloid grinder with a water/milled slurry ratio of 3.5/1followed by filtration through a 100 mesh silk cloth to collect the soy milk for sheet-making.The yield of soluble matters and quality of soy milk were significantly increased resulting in 56.3%increase on the dried soybean sheets.